Dental engine



(No Model.) 2 Sheets-Sheet 1 E. H. BERRY.

DENTAL ENGINE. No. 562,793. Patented June 30, 1896.

(No Model.) 2 Sheets-Sheet 2 F. H. BERRY.

DENTAL ENGINE. 7 No. 562,793. Patented June so, 1896.

ANDREW G GRMMMJHGTOWQWABHINMH, DC

UNITED, STATES PATENT Orricn.

FREDERICK H. BERRY, OF MILVAUKEE, XVISCONSIN.

DENTAL ENGINE.

SIPECIFICATION formingpart of Letters Patent No. 562,793, dated June 30,1896.

Application filed June 17, 1895. Serial No. 552,986. (No model.)

To all whom it may concern:

Be it known that I, FREDERICK H. BERRY, of Milwaukee, in the county ofMilwaukee and State of Wisconsin, have invented a new and usefulImprovement in Dental Engines, of which the following is a description,reference being had to the accompanying drawings, which area part ofthis specification.

My invention has relation to improvements in dental engines.

An object is to provide an improved construction whereby a free and evenmovement of the handpiece in all directions is obtained without thenecessity of employing a long flexible power-conveyor, which flexibleconveyer as ordinarily used is open to the obj ecjection of unevenmovement and backlash.

A further object is to provide an improved construction wherebystraight-ahead drilling may be readily accomplished, and a furtherobject is to provide for automatically lengthening and shortening thedriving-belt with the adjustment of the handpiece.

lVith the above and other objects in View the invention consists of thedevices and parts, or their equivalents, as hereinafter set forth.

In the accompanying drawings, Figure 1 is a side elevation of theinvention. Fig. 2 is a fragmentary view similar to Fig. 1 on an enlargedscale, parts being in section. Fig. 3 is a detail view.'of the innersplit sleeve and the inner section of engine-arm, which it embraces.Fig. at is a lower end view of Fig. Fig. 5 is a view of the lowerportion of the inner section of the engine-arm, showing the forearmpivoted to the lower extremity thereof. Fig. 6 is a section of Fig. 5 onthe line 6 6. Fig. 7 is a side view of the outer portion of the forearm,showing the wristjoint closed and the terminal section turned at rightangles to the forearm. Fig. 8 is a view of that side of the wrist-jointfrom which the stem 17 projects. Fig. 9 is a cross-section on the line 99 of Fig. 8, with one leaf of the hinge opened out. Fig. 10 is a planview of Fig. '7, part in section. Fig. 11 is a sectional view of thedriven pulley, the disks or frames supporting the same and in which ithas its bearin gs, the flexible shaft-casing and its connection with oneof said disks and the haudpiece-casing, disclosing the connectionbetween said flexible shaft, the driven pulley, and the rotary spindleof the handpiece. Fig. 12 is a crosssection on the line 12 12 of Fig.11. Fig. 13 is a cross-section on the line 13 13 of Fig. 8, and Fig. 14is a detail of the lower end of the neck portion 62.

Referring to the drawings, the numeral 13 indicates a rod which isdesigned to be connected up to a swinging bracket. (Not shown.) At theouter end of this rod is fixed a block 14, in which is journaled a shaft15, said shaft carrying at opposite ends pulleys 1G 16, and around whichpulleys an endless cord 17 (shown in Figs. 5 and 6) passes. The block isprovided with depending ears or lugs 18, between which fits the upperend of an enginearm,a pivotal connection being formed by means of atransverse pivot-pin 19. The engine-arm is composed of two parts, theouter tubular part being indicated by the numeral 20. Within this partslides the inner telescoping part 21, which is provided with a reducedportion extending longitudinally thereof for a considerable distance,said reduced portion terminating at the upper end in an enlargementWithin the outer tubular part, and confined between the upper endthereof and the enlarged end of part 21, is a coiled spring The reducedportion of the part 21 is surrounded for a portion of its length by asleeve 24, the lower end of which sleeve is split, as clearly shown inFigs. 2 and 3.

At the lower end of the part 21 of the engine arm is rigidly secured ablock 25, which is intersected by a pin 26, said pinhavingmounted uponopposite ends pulleys 27 27. At the end of the block 25 is pivoted aforearm 28, upon which a sleeve 29 is mounted so as to slide freely.Upon part 21 of the engine-arm is also mounted a sleeve 30, which isheld up to adjusted position by means of a set-screw 31. This sleeve isprovided with a projecting lug 32, into which extends one end of acounterbalancing arm 33,the opposite end of said arm being pivot-allyconnected to an upwardlyextending lug from the sleeve 29. Anon-rotatable shaft 34 passes freely through the .projecting lug 32 andalso through that end of the arm 33 which enters the lug, said armturning on the shaft as a pivot. The shaft 34 is encircled, on oppositesides of the lug 32,

by coiled springs 35 35,the outer ends of which pass into the split endsof shaft 34. These split ends are threaded exteriorly to receive nuts 3636, which nuts firmly bring the split ends together, and thereforesecurely hold the ends of the springs in place in the slots. The innerends of the springs, upon opposite sides of the lug 32,are extended atright angles from the shaft 34, and then bent inwardly and eX- tendedlongitudinally along the edge of the arm 33 for a desired distance. Eachof the springsis bent at right angles across one side of the arm andaround the edge of said arm,and extended a short distance on theopposite side of the arm, as will be clearly seen by reference to Figs.5 and 6 of the drawings. The office of the springs 35 35 is to maintainan upward pressure upon the arm 33,and thereby form a counterbalance forthe weight of the handpiece. By reason of the fact that the sleeve 30is,through the set-screw 31,vertically adjustable on section 21, saidsleeve may be set to suit the weight of different sizes of toolchucks. Avertical adjustment of the sleeve 30 will of course vary the arc of thecircle described, and consequently thereby regulate the balance. As itis not necessary to change the tool-chucks frequently,this adjustment istherefore only required at long intervals.

The outer end of the forearm 28 is formed into a tube 37 ,which isprovided with a series of longitudinal slits 38, and interiorly, at amedial point, with an annular shoulder 39.

Adapted to be connected to the tube 3-7 is a peculiar form of hinge,which constitutes the wrist-joint between the forearm and the handpiece,the parts of which will now be de scribed.

The numerals 4O 40 indicate'two leaves, each of which terminates at oneend in an interiorly-threaded eye 41.

The numerals 42 indicate short pins, four in number, the inner ends ofwhich are adapted to pass through openings in connecting-links 43, andare threaded at their extremities to engage the female threads of the ieyes of the leaves. The pins are also provided medially with shoulders4%, bearing against the links and holding them to place. The free end ofeach leaf is rounded slightly to fit the rounded contour of the eye ofthe other leaf.

The numerals 45' indicate small guide-pulleys, the hubs of which fit andturn upon the pins 42. Against the outer ends of these hubs the heads ofscrews 46 bear, the ends of said screws engaging threaded openings inthe ends of the pins. Rigidly connected to leaf 40 is a stem 47. Thisstem is adapted to enter the bore of tube 37. The end of this stemisrounded slightly, and just back of the rounded end is provided with anannular groove 48. WVhen the stem is inserted into the tube, thisrounded end, by reason of the provision of the longitudinal slits,spreads the annular shoulder 39, and as the stem is further forcedinward, the annular groove 48 is engaged by the annular shoulder 39.From this construction it will be seen that the stem is free to rotatewithin the tube, but can only be withdrawn therefrom by the applicationof considerable power.

The numerals 49 49 indicate two disks rigidly connected together andheld at a desired distance apart, by means of plates 50 50, screwedthereto, the whole forming a bearing-frame for the driven pulleyhereinafter referred to. Plate 50 is riveted, or otherwise suitablysecured, to the leaf 40. Between the two disks is arranged a pulley 51.This pulley has projecting from one face a conical hub 52, which isreceived in an inwardly-projecting tubular lug 53 from the disk 49. Theopposite face of the pulley is provided with a conical recess 54:,adapted to i receive the conical end of a screw 55, which passes throughthe disk 49. By this means i an adjustable cone-bearing is formed. Theouter threaded end of the screw is adapted to receive a nut 56, whichholds the screw to adjusted position. The outer face of disk i 49 isprovided with an annular recess 57, hav- ;ing an outer depending annularflange 5S, formed by the sheathing or covering 59 of the disk. VVit-hinthis annular recess fits freely ;-a head 60, said head having a reducedpc- 1 ripheral portion fitting back of the annular Z flange 58. Thisreduced peripheral portion forms a shoulder 61 to receive the edge ofthe flange.

The numeral 62 indicates a flexible shaftcasing, one end, or the neckthereof, being curved to about one-fourth of a circle, and connected tothe head 60. This flexible shaft- 5 casing is provided medially with anenlargement 63, and the top of its neck portion is left with alongitudinal opening, which is i filled by means of a plate 64,connected at opposite ends, respectively, to the head and .to theenlargement 63. The flexible shaft- 1: casing continues from its neckportion in a straight line, and near its lower end is pro- 5 vided withan annular groove 65. i

The numeral 66 indicates a sheathing or casing, which at its upper endfits freely and revolubly in a groove upon the under side of theenlargement 63. This sheathing or casing is provided with aninwardly-extending round ed bead 67, which fits within the annular igroove 65, and thereby provides for the lower part of the neck rotatingwithin said sheathing or casing, but held against longitudinal 1separation. The lower end of the sheathing 66 is enlarged and providedwith internal threads adapted to engage the threaded end of thehandpiece-casing 68. The outer portion of this enlargement is preferablymilled to provide for firmly and conveniently hold- 1 ing it againstrotation when the handpiececasing is being screwed thereto.

Within the neck 62 is a flexible shaft, preferably consisting of acoiled spring 69, the upper end of which passes through the disk 49 andenters the conical hub 52 of the pulley 51.

' A set-screw 70 passes through the pulleys and engages the end of thespring. \Vithin the handpiece-casing is disposed the rotary spindle 71of the handpiece, the upper reduced end of said spindle extending intothe flexible shaft-casing and having threads adapted to engage the lowerend of said flexible shaft.

From the preceding description it will be seen that I have described adental engine in which a series of arms or sections are employed, theouter or last section being, and for convenience here designated, as theterminal section.

The endless cord 17, it will be understood, leads from a suitable sourceof power and extends over one of the pulleys 16, thence down and beneathone of the pulleys 27, thence up to and between two of the smallguide-pulleys -15, thence around driven pulley 51, thence back betweenthe other two guide-pulleys 45, then down to and around the other pulley27 then upwardly and around the other pulley 1G, and finally backto thesource of power. This cord is at all times automatically held taut bythe spring 23, owing to the constant pressure of said spring upon thetelescoping part 21. All looseness of the belt is there fore effectuallyguarded against. The split sleeve 2st performs an important function inthat while not interfering with the free rota tion of the telescopingpart 21, yet, in case of breakage'of the cord, the two telescoping partswill not separate, owing to the pressure of the split end of the sleeveagainst the outer tubular part 20 of the engine-arm. The same functionis also performed by the longitudinal slitted tube 37,in. connectionwith the stem 47.

In the form of dental engine in which a long flexible shaft is employedthe backlash which 7 such shaft engenders and the jerky motion it causesare objectionable. In myinvention the improved construction substitutedfor such flexible shaft brings the driven pulley and the operating-cordclose to the tool. This arran gement obviates the jerky motion referredto, and instead thereof a steady action is obtained.

It is further to be noted that by my improved construction I obtain allthe movements of which the flexible shaft ordinarily employed iscapable. In the first place, it will be noted that the telescoping part21 has rotary motion in the tubular part 20. Again, the fore-arm 28 hasa swinging motion at right angles to the axis of rotation of thetelescoping part 21. The stem 47 has rotation at right angles to theswing of the forearm-2S. The neck has a complete circular rotation inthe annular recess of disk 49, and the two disks, in turn, are capableof swinging in a direction at rightangles to the independent rotation ofthe neck, as best illustrated in Fig. 9, which illustrates thehinge-leaf 4.0 opened out, the tension of the belt 17 on one set ofguide-pulleys 45 holding links 43 43 back, so as to embrace oppositeedges of the leaf t0. If it is desired. to swing the handpiece laterallyin the opposite direction, (referring to the same, Fig.9 of thedrawings) power is applied to the handpiece in the proper direction toswing the leaf 40 back to its position between the links 43 43. Thefurther turning of the handpiece will then cause the turning of thelinks 43 43 upon the pin 42 of the leaf i0. It will thus be seen that onone lateral swing a leaf opens out from the links, while on the oppositelateral swing the links open out from one leaf, and the other leaf isheld between the links by the tension of the operating-cord.

Then the hinge is opened in one direction, the belt 17 is guided by theupper and lower pulleys on the corresponding side to the swing, and whenopened in the other direction said belt is guided by the upper and lowerpulleys on that side. It is evident thatwhen the hinge is opened out ineither of the directions just referred to the belt 17 must necessarilybe lengthened somewhat, and the necessary result of opening out thehinge is to effect this lengthening, inasmuch as by opening out thehinge the tension of the belt is increased, and the telescoping part 21thereby forced up into the tubular part. 20 of the engine-arm againstthe pressure of the spring 23. Now, the moment the hinge is opened outto the extent desired, and the swinging motion is stopped, the tendencyof the spring 23 to resume its normal expanded condition will againforce the telescoping part. out-- wardly, and thereby again tighten thebelt, and with the tightening of the belt the hinge is closed at theposition to which the hand piece has been swung, thus relieving thetension of the cord.

The neck portion 62 bent at one-quarter of a circle is an importantfeature of the invention. This curved neck has the eifect of throwingthe line of the handpiece at right anglesto the axis of the drivenpulley, thereby adapting my improved construction of dental engine todrilling straight ahead. The foregoing description will clearly showthat with my improved engine a movement of the handpiece in alldirections is possible, and yet at the same time the long flexiblepower-conveyer heretofore used is dispensed with, thus obviatingbacklashand the uneven movement existing in the class of dental engines referredto.

As the operators fingers grasp the handpiece tightly, near the lower endthereof, it is evident that the straight portion of the flexibleshaft-casing 52, when the handpiece is turned to the difierent positionspermitted by the universal-joint connection, should be permitted toturn, in order to prevent the necessity of the operator unduly anduncomfortably twisting his hand to conform to the adjustment. Therotatable connection between the lower end of the flexible shaft-casing(32 and the outer sheathing 66, hereinbefore described, is thereforeprovided. If the lower portion of the flexible shafbeasing, however,were permitted to make a complete turn, the headed portion at the upperend of said flexible shaft-casing would also completely turn the disks49 49 and the pulley 51 carried by said disks. As the pulleys 27 27 arenot capable of rotation in a plane at ble shaft-casing with a projectinglug "2.

sequently prevent the twisting of the belt.

ent, is

a bearing to which the terminal section is rotatably connected, and awrist-joint con-' nection between the bearing and the section which isin advance of the terminal section,

said wrist-joint connection having oppositelyopening leaves, one of saidleaves connected I to the bearing, and the other leaf connected to thesection which is in advance of the terminal section, substantially asdescribed.

2. In a dental engine, the combination, of a 1 terminal section, asection in advance thereof, i a bearing to which the terminal section isconnected, a driven pulley journaled in the bearing, a wrist-jointconnection between the 1 bearing and the section which is in advance ofthe terminal section, said wrist-joint con- 1 nection havingoppositely-opening leaves, one

of said leaves connected to the bearing, and

the other leaf connected to the section which is in advance of theterminal section, guide pulleys carried by the wrist-joint, and adriving-belt leading from a source of power and passing between one setof the guide-pulleys, around the driven pulley, and back between theother set of guide-pulleys, substantially as described.

3. In a dental engine, the combination, of a terminal section, a sectionin advance thereof,

and a wrist-joint connection having oppositely-openin g leaves, one ofsaid leaves connected to the terminal section, and the other leafconnected to the section which is in advance of said terminal section,substantially section which is in advance of the terminal section,substantially as described.

5. In a dental engine, the combination, of a terminal section, a sectionin advance thereof, a wrist-joint connection having oppositelyopeningleaves connected respectively to the respective sections, and each leafhaving an eye at one end, pins engaging the eyes, and links connectingthe pins and arranged adjacent to opposite edges of the leaves,substantially as described.

6. In a dental engine, the combination, of a terminal sect-ion, asection in advance thereof. a bear-in g to which the terminal section isconnected, a driven pulley journaled in the bearing, a wrist-jointconnection between the bea ring and the section which is in advance ofthe terminal section, said wrist-joint consisting of leaves connectedrespectively to the bearing and the section which is in advance Havingthus described my invention, what 1 I claim, and desire to secure byLetters Patj of the terminal section, each leaf having an eye at oneend, pins engaging the eyes and arranged adjacent to the leaves,guide-pul- 1. In a dental engine, the combination, of a terminalsection, a section in advance thereof,

leys carried by the pins, and a driving-belt running from a source ofpower, and passing between one set of guide-pulleys, thence around thedriven pulley, back between the other set of guide-pulleys, and back. tothe source of power, substantially as described.

'7. In a dental engine, the combination, with a terminal section havinga curved neck at one end, a section in advance of the terminal section,and a rotatable connection between the neck and the section which is inadvance of the terminal section; substantially as described.

8. In a dental engine, the combination, of a terminal section having acurved neck at one end, a bearing to which the curved neck is rotatablyconnected, a section in advance of the terminal section, and awrist-joint connection having oppositely-openingleaves, one of saidleaves connected to the bearing, and the other leaf having a rotatableconnection with the section which is in advance of the terminal section,the rotatable connection between the curved neck and the bearing adapting said curved neck to swing in a circle at right angles to the swingof the wrist-joint. substantially as described.

9. In a dental engine, the combination, of a terminal section having acurved neck at one end, a bearing to which the curved neck is rotatablyconnected, a driven pulley mounted in said bearing, a shaft within theterminal section, said shaft having one end connected to the drivenpulley, a rotary spindle also within the terminal section, to whichspindle the other end of the shaft is connected, a section in advance ofthe terminal section, a connection between the bearing and this sectionwhich is in advance of the terminal section, and adriving-belt,substantially as described.

10. In a dental engine, the combination of disks or plates,-one of saidplates provided upon its inner side with an inwardly-extending tubularprojection, and upon its outer side with an annular recess having anoverlapping outer fiange, a driven pulley arranged between the plates ordisks, and provided with a conical hub fitting the conical tubularextension of one of the disks or plates, a conical screw-bearing for theopposite side of the IIO pulley, a terminal section having a curved neckat one end, said neck provided at its end with an annular head fittingthe annular recess of one of the plates or disks, and lying back of theannular flange thereof, a flexible shaft within the terminal section,one end thereof passing through an opening in the head of the neck andsecured within the conical hub of the pulley, a rotary spindle alsowithin the terminal section and connected to the opposite end of theflexible shaft, a section in advance of the terminal section, and adriving-belt, substantially as described.

11. In a dental engine, the combination, of an engine-arm, a forearmpivoted thereto, a terminal section, a bearing to which the terminalsection is rotatably connected, and a wrist -joint connection havingoppositelyopening leaves, one of said leaves connected to the bearing,and the other leaf having a rotatable connection with the section whichis in advance of the terminal section, said leaves opening in adirection at right angles to the swing of the forearm, and the axis ofrotation of the terminal section being at right angles to the swing ofthe leaves, substantially as described.

12. In a dental engine, the combination, of an engine-arm, a forearmpivoted thereto, and a connterbalancing-sprin g having connectionbetween the en ginearm and the forearm, substantially as described.

13. In a dental engine, the combination, of an engine-arm, a forearmpivoted thereto, a counterbalancing-arm having one end connected to theengine-arm and its opposite end connected to the forearm and acounterbalancing-spring having its free end engaging thecounterbalancing-arm, substantially as described.

14:. In a dental engine, the combination, of an engin e-arm, a forearmpivoted theretoy an adjustable collar on the engine-arm, a slidingsleeve on the forearm,a counterbalancing-arm having one end pivotallyconnected to the collar and its opposite end pivotally connected to thesleeve, and a spring having its free end engaging thecount-erbalancing-arm, substantially as described.

15. In a dental engine, the combination, of an enginearm, a forearmpivoted thereto, a shaft carried by the engine-arm, acounterbalancing-arm having one end pivot-ally connected to said shaft,and its opposite end pivotally connected to the forearm, springs woundabout the shaft upon opposite sides of the pivoted end of the arm, saidsprings having their ends extended at right angles from the shaft toengage the counterbalancing-arm, substantially as described.

16. In a dental engine, the combination, of a terminal section,consisting of a shaft-casing and a handpiece-casing, the former providedat its lower end with a projecting lug, a sheathing rotatablysurrounding the shaftcasing, to which sheathing the handpiececasing isrigidly connected, a screw passing through the sheathing, with whichscrew the depending lug is adapted to contact, a hearing to which theterminal section is rotatably connected, a section in advance of theterminal section, and a rotatable connection between the bearing and thesection which is in advance of the terminal section, the plane ofrotation thereof being at right angles to the plane of rotation of theterminal section, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

FREDERICK H. BERRY.

lVitnesses:

ARTHUR L. MonsnLL, ANNA V. FAUST.

